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From: Jason Wessel <jason.wessel@windriver.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: kgdb-bugreport@lists.sourceforge.net,
	Will Deacon <will.deacon@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	linux-arm@vger.kernel.org
Subject: Re: [Kgdb-bugreport] [PATCH 4/5] kgdb: Use atomic operators whichuse barriers
Date: Fri, 02 Apr 2010 15:00:26 -0500	[thread overview]
Message-ID: <4BB64CDA.4000405@windriver.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1004021246470.3634@i5.linux-foundation.org>

On 04/02/2010 02:47 PM, Linus Torvalds wrote:
>
>> From: Jason Wessel <jason.wessel@windriver.com>
>> Subject: [PATCH] kgdb: Use atomic operators which use barriers
>>
>> The cpu_relax() does not mandate that there is an smp memory barrier.
>> As a result on the arm smp architecture the kernel debugger can hang
>> on entry from time to time, as shown by the kgdb regression tests.
>>     
>
> Now your changelog makes no sense any more.
>   

It is revised now and pushed.  Regression testing on the HW I have has
passed as well now.

For the series the pull looks like:

 drivers/misc/kgdbts.c |    6 ++
 kernel/kgdb.c         |  205
+++++++++++++++++++++++++------------------------
 2 files changed, 109 insertions(+), 102 deletions(-)


Thanks,
Jason.


---
From: Jason Wessel <jason.wessel@windriver.com>
Subject: [PATCH] kgdb: use atomic_inc and atomic_dec instead of atomic_set

Memory barriers should be used for the kgdb cpu synchronization.  The
atomic_set() does not imply a memory barrier.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

  reply	other threads:[~2010-04-02 20:00 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-02 18:32 [GIT PULL] kgdb fixes for 2.6.34-rc3 Jason Wessel
2010-04-02 18:32 ` [PATCH 1/5] kgdb: have ebin2mem call probe_kernel_write once Jason Wessel
2010-04-02 18:32   ` [PATCH 2/5] kgdbts,sh: Add in breakpoint pc offset for superh Jason Wessel
2010-04-02 18:32     ` [PATCH 3/5] kgdb: eliminate kgdb_wait(), all cpus enter the same way Jason Wessel
2010-04-02 18:32       ` [PATCH 4/5] kgdb: Use atomic operators which use barriers Jason Wessel
2010-04-02 18:32         ` [PATCH 5/5] kgdb: Turn off tracing while in the debugger Jason Wessel
2010-04-02 19:12         ` [PATCH 4/5] kgdb: Use atomic operators which use barriers Linus Torvalds
2010-04-02 19:37           ` Jason Wessel
2010-04-02 19:43             ` Linus Torvalds
2010-04-02 19:46               ` Linus Torvalds
2010-04-02 20:07                 ` Linus Torvalds
2010-04-02 22:25               ` Russell King - ARM Linux
2010-04-02 23:24                 ` Linus Torvalds
2010-04-03 16:08                   ` Russell King - ARM Linux
2010-04-05  9:21               ` Pavel Machek
2010-04-05 14:56                 ` Linus Torvalds
2010-04-02 19:47             ` [Kgdb-bugreport] [PATCH 4/5] kgdb: Use atomic operators whichuse barriers Jason Wessel
2010-04-02 19:47               ` Linus Torvalds
2010-04-02 20:00                 ` Jason Wessel [this message]
2010-04-08 16:27                   ` Dmitry Adamushko
2010-04-19 15:21               ` Will Deacon
     [not found]           ` <000501cad70a$26ca7e10$745f7a30$@deacon@arm.com>
2010-04-08 14:55             ` [PATCH 4/5] kgdb: Use atomic operators which use barriers Linus Torvalds

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